Knotter for sewing-machines



(No Model) A. W. GOGHRAN. KNOTTER FOR SEWING MACHINES.

" Patented June 9,1891.

F STATES PATENT OFFICE.

ALFRED \V. COOIIRAN, OF BIRMINGHAM, ALABAMA.

KNOTTER FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 453,730, datedJ'une 9,1891.

Application filed May 1'7, 1890. $erial No. 352,116. (No model.)

To all whom it Ynay concern.-

Be it known that I, ALFRED W. COCHRAN, a citizen of the United States,residing at Birmingham, in the county of Jefferson and State of Alabama,have invented certain new and useful Improvements in Knotters, of whichthe following is a specification.

My invention relates to sewing-machine attachments, and has referencemore particularly to a device for uniting in a knot the ends of theupper (needle) and lower or shuttle thread at the beginning andtermination of the seam to prevent raveling. of forming the stitch inshuttle-machines is to use two threads, one passing through an eye nearthe point of the needle and the other carried by and wound upon a bobbinWithin a shuttle vibrating at right angles to the path of the needle.through the fabric to its lowest point and commences to ascend, theneedle-thread (which of course has followed the needle downward, closelypressed against the same) expands and forms a loop. The shuttle nowpasses bodily between the needle and its thread, carrying with it andpaying out the thread wound upon the bobbin. The needle continuing toascend draws the two threads tightly together, and the stitch is therebyformed. The fabric rests upon the top of a throat-plate, and the needlepasses through the fabric and through a small hole formed in thethroat-plate, the seam being formed above the upper face of thethroat-plate. As the stitches are formed, the fabric is pushed along byafeed-bar and the under or shuttle thread passes downward through thehole in the throat-plate. At a point half-way between the two extremepoints reached by the shuttle the shuttle-thread becomes slack, beingtaut only at the extreme points; and in carrying out my invention Iseize the shuttle-thread atthis half-way point, where it is loose, andjust before the needle penetrates the fabric, and form a loop in saidthread by twisting it over upon itself by the twister, my twister beingoperated by hand. The needle and its thread then penetrates, first, thefabric, and immediately beneath it the loop in the under thread, whichhas just been formed. The needle then passes on downward to its lowestpoint and begins to ascend, the needle-thread leaving the needle Themethod Then the needle descends and expanding to form a loop to bepenetrated by the shuttle, as before. hen the needle ascends, the loopin under the thread contracts, the two threads are drawn together, and aknot formed.

In the drawings, Figure l is a perspective View of my improved device;Fig. 2, a perspective view of the throat-plate, looking from the underside; Fig. 3, a perspective view of the arms of the thread-twister;Figs. 4, 5, 6, and 7, sectional views showing the parts in differentpositions, and Fig. 8 a view illustratin g a slight modification.

A indicates what I term the throat-plate, having two arms a ct separatedfrom each other, as shown in Fig. 2, each of said arms being providedwith a hole or opening 1) to receive the needle. The throat-plate isfurther provided with a longitndinally-extending hole or opening a, theaxis of which is at right angles to the needle-holes Z) l). Formedwithin the walls of the hole or opening 0 are lateral cavities ordepressions (1, while projecting from the end of the plate A around thehole 0 is a hub or tubular extension 6, the outer end of which is madeinclined or camshaped, as

Instead of forming a hub upon the throatplate, the inclined wall f maybe formed in the countersunk and enlarged end of the opening 0, asindicated by the dotted lines in Fig. 6.

B indicates the thread-twister, comprising a body 9 to fit the hub e, ahead or enlargement h, by which it may be turned, a pair of spring-arms1 1', which extend inward between the arms a a of the plate A to graspthe thread passing downward through the latter, and a pin or stud j,which, acting upon the camface f of the tubular hub e, will cause thetwister as a whole to move longitudinally as it is turned.

A spring 7r, secured to the plate A and engaging the twister 13, holdsthe latter normally in the position shown in Figs. 1 and 4-, and alsopresses twister forward when pin has reached the proper point on thecam. The spring-arms i i are provided with shoulders or lugs Z l, which,as shown in Fig. at, normally lie within the cavities d (I, so thatordinarily the arms '1: i will be separated; but it will be observedthat when these lugs Z Z are not in the cavities but are in the holeproper e, the

arms '5 i will be closed or forced toward each other, as shown in Fig.5.

The operation is as follows: \Vith the parts in the position shown inFig. 4 the'twister B is pushed inward longitudinally, so that the lugs ZZ will ride out of the cavities cl d and cause the armst' to take thethread between their innerends, as shown in Fig. 5,the twister beingshown as at the limit of its inward movement. The twister is now turnedby hand to the left, as indicated by the arrow in Fig. 6, in orderto-form a loop in the thread; but it will be observed that as thetwister is thus turned or rotated its pin or studj, riding along the camor incline f, will cause the twister to also move outward. If thetwister were moved outward without being turned or rotated, the lugs ZZwould drop into the cavities d d; but by turning or rotating thetwister to form a loop in the thread this is avoided, for thecam-surface is so made that when the twister has made about one-quarter(i) of a complete revolution or rotation the twister will have beenmoved outward far enough to prevent the lugs Z entering the cavities.Another efiect of the gradual withdrawal backward of the twister by thecam is that it forms a bow in the under thread at a point between thetwo arms of my throat-plate and brings the points of each spring-armback behind the thread grasped between them, and allows the latter topass over these points, and thus facilitates the formation of theloop.Continuing the revolution or rotation of the twister will bring the studj into such position that the spring 70 or the operator may move thetwister forward lengthwise sufficiently to bring the open loop directlyin line with the openings 1) h, as shown in Fig. 7. At this point thelugs drop into the recesses or cavities 01 (Z and permit the arms toseparate. While in this position, the needle descends to its lowestpoint, and after the shuttle moves forward the needle ascends. The loop,which is always made in the under thread is then lifted off the ends ofthe spring-arms by the ascending needle-thread just before the tensiontakes effect, this action resulting in the formation of a sailors knot.The ends of the arms '5 i are preferably notched, as at m, in order totake a better hold upon the thread in forming the loop, but they do notprevent the disengagement of the loop from the arms. The cavities d dare long enough to allow the arms '1 i to remain open until the threadis provided with lugs 77. n, which, while not preventing the arms fromcoming together, effectually preclude the entrance or passage of thethread behind the lugs. This construction avoids the necessity ofthreading the thread through the opening in the arm a.

It is obvious that many other forms of twister than that shown can beused with the throat-plate herein shown and described, and while Iprefer to use the present form of twister, I do not wish to beunderstood as limiting myself to the use of the special twister with myimproved throat-plate.

Having thus described my invention,what I claim is 1. In combinationwith the throat-plate A, having two arms a, a, and openings for theneedle in said arms, a twister journaled in the body of the throat-plateand extending inwardly between the arms.

2. In combination with a twister, the throatplate A, provided withperforated arms a a, a longitudinal opening 0, lateral cavities d, and acam-face f.

3. In combination with a throat-plate, the twister B, comprising a mainbody g, and

two spring-arms i 1', having lugs or projec tions Z Z.

4. In combination with plate A, having hub 6, provided with cam-face f,twister B, provided with spring-arms 'i 5, and stud j, and a spring is,arranged substantially as shown.

5. In combination with plate A, having the perforated arms a a and therecessed opening 0, a twister B, provided with spring-arms i i, and lugsZ Z. I

6. In combination with a throat-plate provided with the openings orholes I) for the needle, a manually-operated twister journaled in themain body of the throat-plate and projecting inwardly into line with thethread-openings, but at right angles thereto.

7. In combination with a throat-plate having two separated arms a a,adapted to receive and hold the thread, and also provided with acam-face f, a twister mounted in the plate and adapted to movelengthwise and also to be rotated relatively to the plate, and a springacting upon the twister, all substantially as shown.

8 In combination with a throat-plate having two separated thread-holdingarms a a, a twister mounted therein and provided with two springsarmsadapted to work between the thread-holding arms a a, and means,substantially such as shown, for moving the twister inward and outwardand opening and closing its arms as it is turned or rotated.

In witness whereof I hereunto set my hand in the presence of twowitnesses.

ALFRED IV. COOHRAN. Witnesses:

- W. I. GIBsoN, P. M. AGAN.

